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  • Polymer and Materials Science  (11)
  • hydrogen evolution  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Comparative study of nanocrystalline Ti2RuFe and Ti2RuFeO2 electrocatalysts for hydrogen evolution in long-term chlorate electrolysis conditions (1999)
    Springer
    Journal of applied electrochemistry 29 (1999), S. 551-560 
    Details
    ISSN: 1572-8838
    Keywords: ball-milling ; electrocatalyst ; hydrogen evolution ; nanocrystalline alloy ; sodium chlorate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Ti2RuFe and Ti2RuFeO2 nanocrystalline alloys were prepared by high energy ball-milling and used as cathodes for the hydrogen evolution reaction (HER) in the process of sodium chlorate synthesis. Ti2RuFe is almost single phase with the B2 structure. In contrast, Ti2RuFeO2 is made of a mixture of Ti2RuFe and TiOx phases. Tests in chlorate electrolysis conditions did not show any sign of degradation of Ti2RuFeO2 over a 300 h period, while Ti2RuFe breaks down after less than 100 h. The degradation of Ti2RuFe occurs because of hydrogen absorption and desorption during alternating hydrogen discharge and open-circuit conditions. Various hypotheses to explain the increase stability of the O containing alloy are considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026441532352
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  • 2
    Electronic Resource
    Electronic Resource
    Large specific surface area nanocrystalline Ti–Ru–Fe cathode materials for sodium chlorate (1999)
    Springer
    Journal of applied electrochemistry 29 (1999), S. 627-635 
    Details
    ISSN: 1572-8838
    Keywords: ball-milling ; electrocatalyst ; hydrogen evolution ; leaching ; lixiviation ; nanocrystalline alloys ; sodium chlorate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Ball-milled nanocrystalline Ti3RuFe powders were mixed with 1, 2, 4, 10 and 20 equivalents of Al and the mixtures were milled again for 20 h. The amount of Al atoms dissolved into the B2 structure of Ti3RuFe does not exceed 8–9 at %, the remaining being present as elemental Al into the powder mixture. During a subsequent treatment of the composite powder in alkaline solutions, the elemental Al is leached out, while Al solutes in the B2 structure are not affected. An examination of the surface by scanning electron microscopy reveals that the leached powder has a highly porous surface structure. Surface area measurements performed by BET measurements show that there is a tenfold increase in the effective surface area. Activated electrodes made from these porous materials show a significant decrease of the cathodic overpotential for hydrogen evolution in typical chlorate electrolysis conditions of about 80 mV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026408502373
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of oxygen and titanium contents on the stability of nanocrystalline Ti–Ru–Fe–O cathode materials for chlorate electrolysis (2000)
    Springer
    Journal of applied electrochemistry 30 (2000), S. 491-498 
    Details
    ISSN: 1572-8838
    Keywords: ball milling ; chlorate electrolysis ; electrocatalysis ; hydrogen evolution ; nanocrystalline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Electrodes made from nanocrystalline Ti:Ru:Fe (2−y:1+y/2:1+y/2), with y varying from 0 to 1 by step of 0.25, and Ti:Ru:Fe:O (2:1:1:w), with w varying from 0 to 2 by step of 0.5, were prepared and tested as activated cathodes for the hydrogen evolution reaction in typical chlorate electrolysis conditions. These electrodes were subjected to an accelerated aging test, consisting of a succession of cycles of hydrogen discharge (HER) and open-circuit (OCP) conditions. In addition to monitoring the cathodic overpotential value during the aging test, visual inspection and mass loss measurements were performed on the electrodes at the end of the test to assess their stability. In the case of Ti:Ru:Fe (2:1:1), a large increase of the cathodic overpotential value is observed after 20 cycles. Adding O to the formulation causes a remarkable improvement of the long-term stability of the electrodes. As little as [O] = 10 at.% in nanocrystalline Ti:Ru:Fe:O (2:1:1:w) materials is sufficient for the electrode to show absolutely no sign of degradation after 50 cycles of HER/OCP, the longest accelerated test conducted. Adding more O to the formulation of the material does not lead to further stability improvement. A better stability under the conditions of the accelerated aging test can also be observed for nanocrystalline Ti:Ru:Fe (2−y:1+y/2:1+y/2) materials with y 〉 0. In that case however, the level of improvement is dependent on the value of y. The best results are obtained for y = 0.75. A hypothesis is proposed to explain the improved stability obtained by lowering the Ti content and/or by adding O. The similarity and difference between both ways of improving the stability of the nanocrystalline Ti:Ru:Fe materials are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003961417762
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  • 4
    Electronic Resource
    Electronic Resource
    Synthese und eigenschaften einiger höhergliedriger cyclischer ätheracetale (1977)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 178 (1977), S. 3191-3195 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Optimized syntheses of 1,3,6,9-tetraoxacycloundecane (2), 1,3,6,9,12-pentaoxacylotetradecane (3), and 1,3,6,9,12,14,17,20-octaoxacyclodocosane (4) as well as some physical and chemical properties and the proof of structure are reported.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1977.021781202
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  • 5
    Electronic Resource
    Electronic Resource
    Werner Kern zu seinem 70. Geburtstag (1976)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 177 (1976), S. 1639-1641 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: No. Abstract.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1976.021770601
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  • 6
    Electronic Resource
    Electronic Resource
    Messung elastischer Wellen in Stahl- und Gesteinsstäben mit Hilfe des magnetoelastischen Effektes (1997)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 28 (1997), S. 571-574 
    Details
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Measurements effect of elastic waves in steel- and rock rods using the magneto-elasticStress waves in steel and iron ore rods produced by a mechanical impact can be measured by a sensor using the magneto-elastic effect. A detection of the changing magnetic flux is made. The function describing the propagation of longitudinal waves in rods is known as the stress wave equation. The agreement with theory is verified by examinations of steel rods using strain gauges. Afterwards the signals of three iron ores (magnetite, hematite, siderite) are recorded. Induced voltage is measured by the magneto-elastic sensor in the case of magnetite and hematite, however it is not possible to detect any signal for siderite. This means that the change of magnetic flux depends on the kind of bulk magnetic appearance, not on content of iron.Using the magneto-elastic sensor the magneto-elastic effect offers the possibility to detect tree of contact mechanical waves produced by a mechanical impact in ferro- or ferrimagnetic solids.
    Notes: An Stahl- und Eisenerzstäben werden die durch einen Stoß ausgelösten elastischen Dehnwellen mit Hilfe eines Sensors gemessen, der den magnetoelastischen Effekt ausnutzt. Detektiert wird dabei die Änderung des magnetischern Flusses. Die theoretische Beschreibung der Ausbreitung elastischer Längswellen in Stäben erfolgt mit Hilfe der eindimensionalen Dehnwellengleichung. Die Übereinstimmung mit der Theorie wird exemplarisch durch Untersuchungen an Stahlstäben mittels Dehnungsmeßstreifen verifiziert. Danach werden die Signale von drei Eisenerzstäben (Magnetit, Hämatit, Siderit) aufgenommen. Bei den Gesteinen Magnetit und Hämatit lassen sich mit dem magnetoelastischen Aufnehmer Induktionsspannungen messen, während beim Siderit keine Signale aufgezeichnet werden konnten. Das bedeutet, daß für die Änderung des magnetischen Flusses nicht der Eisengehalt, sondern die Art der äußeren magnetischen Erscheinungsform der Proben entscheidend ist.Der magnetoelastische Effekt bietet somit die Möglichkeit die durch eine Stoßbelastung in ferro- bzw. ferrimagnetischen Materialien ausgelösten mechanischen Wellen berührungslos mit Hilfe eines magnetoelastischen Sensors zu erfassen.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19970281208
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  • 7
    Electronic Resource
    Electronic Resource
    Conformation of amylose in aqueous solution: Optical rotatory dispersion and circular dichroism of amylose-iodine complexes and dependence on chain length of retrogradation of amylose (1971)
    New York : Wiley-Blackwell
    Biopolymers 10 (1971), S. 243-261 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dependence on chain length of two characteristic properties of amylose, i.e., retrogradation and complex formation with iodine, have been studied by using enzymatically synthesized, homodisperse amyloses. The association rates of amyloses in water containing 5% dimethyl sulfoxide have a sharp maximum at a degree of polymerization P̄n of 80; shorter and longer molecules are much more soluble. The iodine complexes of amylose exhibit a strong Cotton effect in the range of the long-wave absorption maximum (position depending on chain length) and two weaker Cotton effects at 480 and 350 nm. The long-wave Cotton effect is most intense at about P̄n 50 and decreases rapidly for shorter and longer chains. This behavior is unexpected and is not in accordance with the further increase of λmax and λmax. The experiments can best be interpreted by assuming well ordered, stiff chains in the low molecular weight range (P̄n 50-80). For longer chains, the findings are discussed in the light of current concepts of amylose conformation in aqueous solution, namely the model of the broken helical chain (alternating stiff helical segments and unordered regions) and the model of a flexible coil without a significant helical content. However, according to the results given in this paper, a wormlike helical chain seems to be the most adequate model for amylose conformation in neutral solution.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360100203
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  • 8
    Electronic Resource
    Electronic Resource
    The hole concentration on oxygen sites in teh high Tc superconductor YBa2Cu3O7-x (1988)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 12 (1988), S. 326-326 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740120514
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  • 9
    Electronic Resource
    Electronic Resource
    Macromolecules with groups of high reactivity (1960)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 48 (1960), S. 91-99 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Reactions on the reactive groups of macromolecular substances (e.g., cellulose) have long been known, even since before the structures of macromolecules were understood. H. Staudinger carried out numerous reactions with macromolecules, maintaining the degree of polymerization constant, in order to substantiate the macromolecular structure of the substances investigated (polymeric-analogous reactions). During the last fifteen years reactions with macromolecules have been investigated because it was desirable to compare the chemical diversity of low molecular weight compounds with the corresponding chemical diversity of macromolecular compounds. These endeavors bring forth materials which supplement the numerous macromolecular substances which are produced and used as materials for plastics, and therefore these materials should have as low reactivity and high stability as possible. Objectives are given for the preparation of macromolecules with a large variety of groups. From these objectives it is evident that, as in low molecular weight chemistry, macromolecular substances which possess functional groups of high reactivity are suitable as starting materials. Some of these which have been known for a long time but have been investigated only in recent years are polyaldehydes (polyacroleins and polymethylacroleins), polyacyl halides such as polyacryl chlorides and polyvinylsulfonyl chlorides and fluorides, and, most recently, polymeric organometallic compounds such as poly-p-lithiumstyrene. The reactions with these macromolecules are described and the properties of the resulting new polymeric substances are given.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1960.1204815010
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  • 10
    Electronic Resource
    Electronic Resource
    Optische rotationsdispersion und circulardichroism us der jodkomplexe niedermolekularer amylosen in abhängigkeit vom polymerisationsgrad. 4. Mitteilung3. Mitt., R. C. SCHULZ, R. WOLF und H. MAYERHÖFER, Kolloid-Z. u. Z. Polymere 227 (1968) 65.Frau Professor Dr. E. HUSEMANN mit freundlichen Grüßen zum 60. Geburtstag gewidmet (1969)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 121 (1969), S. 147-158 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: From a series of enzymatically synthesized amyloses with a very narrow molecular weight distribution (Pw/Pn = 1.001-1.002) and degrees of polymerization (Pn) between 25 and 480 the iodine complexes were prepared. The absorption spectra as well as the ORD- and CD-curves of these complexes were recorded. COTTON effects were observed at 365, 485 and in the range of 500-600 mμ. The wavelength of the absorption maximum (λmax) of greatest wavelength and of the positive CD-maximum in the region of 500-600 mμ may be described as functions of Pn by the equation : \documentclass{article}\pagestyle{empty}\begin{document}$$\frac{1}{{\lambda _{\max } }} = \frac{1}{{\rm A}} + \frac{{\rm B}}{{\rm A}} \cdot \frac{1}{{{\rm P}_{\rm n} }} $$\end{document} Furthermore, the extinctions, the base molar rotations and dichroic absorptions have been evaluated as a function of Pn. The base molar rotations and the CD-absorptions exhibited a maximum between Pn 70 to 100 and decreased again at higher Pn. ORD and CD increased on standing of the solutions, whereas the locations of the absorption maxima as well as of the COTTON affects remained unchanged. Possible reasons for this behaviour are discussed.
    Notes: Von einer Reihe enzymatisch synthetisierter Amylosen mit sehr enger Molekulargewichtsverteilung (Pw/Pn = 1,00 bis 1,002) und Polymerisationsgraden (Pn) zwischen 25 und 480 wurden die Jodkomplexe hergestellt. Die Absorptionsspektren sowie die ORD-und CD-Kurven dieser Jodkomplexe wurden aufgenommen. Es treten COTTON-Effeket auf bei 365, 485 und im Bereich von 500-600 mμ. Die Wellenlänge des langwelligen Absorptionsmaximums (λmax) sowie des positiven CD-Maximums als Funktion von Pn lassen sich durch folgende Gleichung beschreiben: \documentclass{article}\pagestyle{empty}\begin{document}$$ \frac{1}{{\lambda _{\max } }} = \frac{1}{{\rm A}} + \frac{{\rm B}}{{\rm A}} \cdot \frac{1}{{{\rm P}_{\rm n} }} $$\end{document} Ferner wurden die Extinktionen, die grundmolaren Drehwerte und die CD-Absorptionen als Funktion von Pn untersucht. Drehwerte und CD-Absorption durchlaufen zwischen Pn 70 und 100 maximale Werte und sinken bei höherem pn wieder ab. Sowohl ORD als auch CD nehmen im Laufe der Zeit zu, obwohl die Extinktionen und die Lage der Absorptionsmaxima und der COTTON-Effekte unverändert bleiben. Mögliche Ursachen werden diskutiert.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1969.021210113
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